Metal framed facade panel and facade covered with such a panel

ABSTRACT

The panel comprises an outer plate (70) supported by a metal frame (71). Two opposite sides of the frame are formed by light metal profiled elements (72, 73) having a rim (74) which extends along one edge (75) of the outer surface of the plate. This rim may be bevelled or right-angled. The plate is clamped between the opposing rims (74) by means of two threaded steel rods (76). The other two edges of the panel are devoid of any metal element. The panel (62) may be placed on the front of a window (63) or an opaque part of the facade. This panel makes it possible to attach, without the use of glue, thin facade facing plates, particularly plates of glass or stone, so that they are virtually the only visible parts of the facade.

The present invention concerns a facing or window panel designed to forma prefabricated element of the exterior surface of a building facade andcomprising at least one rectangular exterior plate, especially of glass,stone, fibro-cement, synthetic material or the like, and a metal framesupporting the said exterior plate provided with means for attaching itto a facade structure or to a window, said frame comprising metal rimshooked to at least two opposite edges of the exterior plate.

The invention also concerns a building facade covered with panels ofthis type.

For covering facades, the use of glass plates or thin plates made ofstone or other similar materials such as fibro-cement is becoming moreand more common in order to profit from their esthetic and technicalproperties, particularly their thermal and acoustical qualities, theirdurability and easy cleaning. To achieve optimal technical and estheticresults, it is desirable that the spaces between plates be as small aspossible.

One known solution consists of attaching to a facade structureprefabricated panels with a metal frame to which the exterior plate isglued. Such panels with glued plates, however, have variousdisadvantages due to the fragility of the plate edges, the longtermunreliability of the glue, and also the difficulty of replacing a plateafter eventual deterioration. For these reasons there is a tendency toabandon this solution in favor of plates with a frame having edges whichhook firmly to the plate edges. For example, Patent Application GB-A-2155 981 describes prefabricated glazed panels with a metal framesurrounding the exterior plate and a right-angled edge extending infront of the exterior surface of the glass. This edge is visible, breaksthe unity of appearance on the facade and may cause a disturbingreflection. Furthermore, it interferes with cleaning the exterior platesurface.

To overcome these disadvantages, Patent Application FR-A-2 619 587proposes a type of panel wherein the edges of the exterior plate have abevel on the side for the building exterior. The metal frame edge coversthe plate only in front of this bevel in such a way that it does notproject from the flat exterior surface of this plate. Nevertheless thismetal rim, which cannot be reduced indefinitely in size since it holdsthe plate, remains visible from the outside. Moreover, since the frameis generally made of light metal, it undergoes thermal expansion, theamplitude of which is a multiple of plate expansion. Therefore it isnecessary to interpose between each rim and the plate a profiledelastomeric element which absorbs the expansion differences butincreases the thickness of the visible frame portion.

Austrian Patent AT-B-379 186 describes a facade covering formed of glassplates which may have two unattached vertical edges, but they are notprefabricated panels with their own frames. The plates are supported byhorizontal profiled elements which have been previously attached to thefacade and which have oblique opposing rims, so that each plate may beinserted by sliding it horizontally between two opposite profiledelements and then sealed to them by means of an elastic mass.

The goal of the present invention is to overcome the disadvantages ofthe prior art by perfecting a panel of the type described in thepreamble and reducing visible frame parts insofar as possible so as toachieve a facade on which virtually only the exterior panel plates arevisible. A secondary goal consists of disposing the frame so thatdifferential expansion between the frame and the plate is reduced.

To achieve this, the panel according to the invention is characterizedin that the metal frame comprises at least one pair of support elementsprovided with the said rims and disposed on two opposite edges of theexterior plate, and traction elements connecting the two supportelements in each pair so as to pull them toward each other and clamp theexterior plate between the said rims.

Each one of the traction elements advantageously comprises a steel rodwhich may have threaded extremities passing through transverse holes inthe said support elements and provided with tightening screws. Inanother execution, the said traction elements may comprise at least onesteel cable.

In a first advantageous embodiment, the panel support elements comprisetwo metal profiled elements disposed along two first opposite edges ofthe exterior plate, and at least two traction elements disposed inparallel to the two other edges of the exterior plate, said two otheredges being unattached to any frame element outside the area of theplate angles. Each one of the support elements may comprise, at at leastone extremity of the said profiled element, a transverse stop abuttingthe plate edge which is perpendicular to the said profiled element.

In another form of embodiment, the support elements of a panel comprisefour angled pieces connected in twos by the traction elements, each onehaving two of the said edges, perpendicular to one another, for hookingonto an angle of the exterior plate, and the four edges of the saidplate are unattached to any frame element between the angled portions.

The said exterior plate may be the exterior glass of double glazedinsulating glass, such as that of a window.

The said exterior plate may be made of plate glass.

In a particular embodiment, one of the elements of the said pair ofsupport elements is provided with hinges disposed to support the paneland allow it to pivot, the other element of the pair being provided withlocking means to selectively block pivoting of the panel.

According to another feature, the invention concerns a building facadecomprising a facade structure and an exterior facing consisting ofpanels such as those defined above, which are attached to saidstructure.

Preferably, the said support elements of the panel's metal frame arehooked at their rims onto at least two opposing vertical edges on theplate of the exterior panel and are connected by horizontally disposedtraction elements, the horizontal edges of said plate being unattachedto any frame element outside the area of the plate angles.

According to a particularly simple means of attachment, the said panelattachment device consists of supports attached to said structure whichare provided with upwardly facing hooks to engage the traction elementsof the panel frame.

In a preferred embodiment, said structure comprises a wall having atleast one window, said exterior facing consists of panels of plates ofglass, and these plates form a vertical screen extending in front ofsaid wall and the window and are separated from them so as to formventilation space between them and the screen.

In a first specific facade embodiment, the said window comprises anon-working frame and a frame opening on a vertically pivoting axis, andone of the panels of the exterior facing, situated in front of thewindow, is supported by the opening window frame so that it can pivotwith it toward the inside of the building. Preferably, one of the saidsupport elements on the panel frame is provided with hinges on avertical axis, the means for attaching the panel consists of metalbrackets holding said hinges and attached to the opening frame of thewindow, and in the area of said hinges, the panel extends in front ofthe non-working frame of the window so as to hide it. Said metalbrackets may be angled to form, between the window and the panel, aspace forming a housing for an awning.

In a second specific embodiment, one of the panels of the exteriorfacing, situated in front of the window, is movably attached to saidstructure in relation to the adjacent panels situated above and belowit, said panel being movable between a first position where its glassplate is in the same vertical plane as those of the adjacent panels, andat least one second position where at least the lower edge of said plateis distances from said vertical plane and leaves an air passagewaybetween the ventilation space and the exterior air, said panel beingconnected to a manual or motorized control means. The movable panel maybe movable in the horizontal direction, perpendicular to the facade,while remaining parallel to itself. The said movable panel may beconnected to a movable element on a deflector disposed along one loweredge of the window so that, in the movable panel's second position, thedeflector extends above the ventilation space so that it can deflect acurrent of air in that space toward the outside.

The present invention and its advantages will be more readily apparentfrom the following description of various exemplary embodiments, withreference to the attached drawings, wherein:

FIG. 1 is an elevational representation of a portion of a facade coveredon the outside with panels according to a first embodiment of theinvention;

FIG. 2 is an elevational view of the interior surface of a facing panelfor the facade of FIG. 1;

FIG. 3 is a horizontal cross-section taken along line III--III of FIG.1;

FIG. 4 is a vertical cross-section taken along line IV--IV of FIGS. 1and 3;

FIG. 5 is a view analogous to FIG. 1 and shows another embodiment ofpanels according to the invention;

FIG. 6 is a schematic vertical cross-section taken along line VI--VI ofFIG. 5;

FIG. 7 is a horizontal cross-section taken along line VII--VII of FIG.5;

FIG. 8 shows the object of FIG. 7 in the open window position;

FIG. 9 is a transverse cross-section of a panel edge in anotherembodiment;

FIGS. 10 and 11 are schematic vertical cross-sections showing anotherembodiment of the invention in which a glass facing panel is movablebetween two positions respectively shown in these figures;

FIG. 12 is an enlarged vertical cross-section showing a portion of FIG.10 in greater detail;

FIG. 13 is a horizontal cross-section of the detail of the area of avertical edge of the movable panel shown in FIGS. 10 through 12;

FIGS. 14 and 15 are vertical cross-sections taken along lines XIV--XIVand XV--XV of FIG. 13;

FIG. 16 is a schematic elevation of the interior surface of anotherfacade facing panel according to the invention, having a frame formed offour angled portions connected by rods;

FIG. 17 shows a perspective of one of the angled portions;

FIG. 18 is a horizontal cross-section of an angled portion of the panelof FIG. 16;

FIG. 19 is a schematic view illustrating an attachment means for thepanel of FIG. 16; and

FIGS. 20 and 21 are views analogous to FIG. 16 and show two otherembodiments of the panel frame.

FIG. 1 shows the exterior appearance of a facade covered with opaqueplates, preferably of colored fibro-cement, by means of prefabricatedpanels 1 which are attached in front of the opaque facade portions, thefacade being ventilated behind these panels. Panels 1 are separated byhorizontal and vertical intervals 4 and 5 forming hollow joints whichare seen only as thin dark lines when one is some meters away from thefacade. The exterior surface of each panel is in the same plane as thatof the adjacent panels. The panel dimensions are not critical in thepresent invention. Specifically, depending upon the case, panel heightmay correspond to window height, back plate height or the height of anentire story.

FIG. 2 shows construction of panel 1 in principle, comprising anexterior plane plate 10 of fibro-cement and a metal frame 11 applied tothe back of plate 10. Frame 11 is composed of two parallel supportelements 12, consisting of light metal profiled elements disposed alongthe two vertical edges of plate 10 and provided with rims hooked ontothese edges, and of two horizontal steel rods 13 forming tractionelements which pull support elements 12 toward each other so as to clampplate 10 between them. In this way, frame 11 leaves horizontal edges 14and 15 of plate 10 unattached.

In FIGS. 3 and 4 there is shown more detail of the construction ofpanels 1 and how the facing they form is attached to a facade structurecomprising a wall 16 covered with thermal insulation 16a, horizontalprofiled metal elements 17 attached to the wall, and vertical profiledmetal elements 18 attached to profiled elements 17 by means of angleplates 19. In each panel 1 an elastomeric strip 21 is interposed betweenplate 10 and each profiled element 12. This profiled element is providedwith an oblique rim 22 in abutment, by the intermediary of strip 21,with the corresponding vertical edge 23 of plate 10, which is bevelledso that the plate does not slide forward, while also preventing rim 22from extending beyond the plane of exterior surface 24 of plate 10.Profiled element 12 has two parallel flanges 25 and 26 on the side ofthe facade structure. Rods 13 pass through holes disposed in flanges 25and 26. Each of their extremities is threaded and has a self-blockingscrew 28 abutting flange 25, preferably by means of flexible washers 29.Screws 28 are tightened with a predetermined force which compressesplate 10 between the two opposing rims 22. With this arrangement 22,plate 10 may be held in the frame solely by friction. However, in thisexample, the lower extremity of each profiled support element 12 has anangle plate stop 30 with a horizontal flange engaged under the loweredge 14 of plate 10 and a vertical flange housed between profiledelement 12 and plate 10 and having a horizontal peg 32 engaging in ahole in profiled element 12. This simple construction of metal frame 11allows the conventional profiled elements covering horizontal edges 14and 15 of exterior plates 10 to be dispensed with. These two edges donot need to be bevelled and they may be devoid of any visible elementmade of metal, synthetic or other material along horizontal spaces 4.Along vertical spaces 5, only the small oblique rims 22 of the frame arevisible.

To support facing panels 1, metal supports 33 are attached in knownmanner in adjustable positions along vertical profiled elements 18. Eachsupport 33 comprises, depending upon its position in the facade, one ortwo upwardly facing hooks 34. Each horizontal rod 13 in panels 1 simplyengages from top to bottom in two hooks 34, each of which is insertedbetween flanges 25 and 26 of corresponding profiled element 12.

Aside from the esthetic advantages mentioned above, it is noteworthythat this construction of metal frame 11 allows plate 10 to be flexiblyclamped in the frame thanks to the elasticity of elastomeric profiledelement 21 and of washers 29, thereby eliminating any ulterior playbetween the frame and the plate, as well as any problem of thermalexpansion differentials between the frame and the plate. Moreover, theattachment means described is extremely simple and also permits easyreplacement of a damaged plate, since it is necessary only to unhook thecorresponding panel and loosen screws 28 to remove plate 10 from theframe and replace it with a new one.

In another form of embodiment shown in FIGS. 5 through 8, a facing orscreen of glass plates is formed on a building facade by facing panels61 and 62. As shown in FIGS. 5 and 6, each of panels 62 is attached infront of a window 63 shown by dotted lines in FIG. 5, while panels 61are attached in front of the opaque portions 64 of the facade. Seen fromthe outside, panels 61 and 62 are separated by horizontal spaces 65 andvertical spaces 66 comparable to spaces 4 and 5 described above. Thehorizontal spaces 65 are defined only by the glass plates, and not bythe rims of the panel frames.

As is seen in FIGS. 7 and 8, each panel 62 comprises an exterior facingplate 70 made of glass, attached to a metal frame 71 formed essentiallyof two parallel profiled columns 72 and 73 made of light metal, eachhaving an oblique rim 74 extending in front of a bevel 75 on a verticaledge of plate 70, and of at least two adjustable horizontal rods 76connecting the two columns 72. Rods 76 are stainless steel and havethreaded extremities 77 which pass through transverse holes in columns72 and to which screws 78 are connected for creating a permanenttraction in rods 76 ensuring that plate 70 is clamped between rims 74 ofthe two opposing columns 72 and 73. In the drawing it is apparent thateach column 72, 73 has a flat face 79 abutting the back of plate 70. Athin connection of synthetic rubber 80 is interposed between plate 70and the profiled column 72, 73, along surface 79 and rim 74.

The two horizontal edges of plate 70 do not need to be bevelled and maybe devoid of any visible frame element. Naturally, panels 61 may havemetal frames designed in the same way, so that horizontal space 65separating the glass plates of the two superimposed panels 61, 62 isfree of any attachment device and at the same time, may be very narrowand barely visible. The simple construction of metal frame 71 alsoresolves all the problems of expansion and tolerances in manufacturingthe panels, thereby allowing the use of bevelled glass with completesecurity. Note that with such a system of metal framework, the facingplates may be attached by being clamped between the rims along theirhorizontal edges, and their vertical edges would then be devoid ofattachment devices and of any metal elements.

In this example, as is shown specifically in FIGS. 6 and 7, each facingpanel 62 is attached to an opening frame 82 on the window 63, and not tothe non-working frame 83 supporting frame 82 by means of hinges 84which, in the present case, have vertical axes. In actuality, column 72of panel 62 is articulated, by the intermediary of hinges 85, to atleast two metal clamps 86 attached to frame 82 of the window, whilecolumn 73 is supported by two other metal clamps 87 attached to theopposing column of frame 82. Column 73 is locked to clamps 87 by mealsof sliding pegs 88 which may be displaced by pushing a recall spring(not shown) to unhook panel 62 and allow it to pivot on hinges 85 whenit must be separated from window 63 for maintenance operations. As isshown in FIG. 7, this allows maintenance personnel to access panel 62from inside the building by opening window 63 with a handle 89, thenmaking panel 62 pivot in relation to the window while it is inside. Allthe glass surfaces may be cleaned from inside the building, also,including the two surfaces of exterior glass plate 70.

In FIG. 7 note that clamps 86 are long enough so that column 72 of theframe of panel 62 covering the right window is in front of thenon-working frame 83 of the left window, so that vertical space 86 issituated practically opposite the vertical connection between theopening and non-working portions of the left window. This allows opaqueportions 82 and 83 to be effectively hidden behind panels 62, while alsoallowing the right column 73 of each panel to penetrate the buildingwhen the window is opened.

In addition, FIGS. 6 and 7 show that clamps 86 and 87 are long enough inthe direction perpendicular to the facade to form between each panel 62and the corresponding window 63 a space 90 wide enough to house anawning 91 including its lateral guide rails 92 and its roller casing 93.In the drawings, the broken lines are a schematic representation of theaxes 94 and 95 of a conventional awning control mechanism attached toframe 82 of the window.

FIG. 9 shows an embodiment of a panel of the same type as panel 62described above, but in which the glass plate 70 with bevelled verticaledges is replaced by a plate 100 of plate glass, comprising an interiorlayer of glass 101, an intermediate layer of non-tearing syntheticmaterial 102 and an exterior layer of glass 103. Along the verticaledges of plate 100, the interior layer 101 extends beyond layers 102 and103, thus creating a tiered shape eliminating the need for a bevel,always delicate to make. The profiled column 72 of the metal frame ofthe panel comprises a suitable oblique rim 104 which extends in front ofprojecting edge 105 of the glass layer 101, surrounded by the rubberjoint 80. The extremity of rim 104 is provided with a flexibleconnection 106 abutting the perpendicular edge of layer 103 and ensuringthat the tightening effect of screws 78 is transmitted first of all tolayer 101 of the plate glass plate. Naturally, the same type of plate100 and rim 104 may be provided on fixed panels 61 of FIGS. 5 and 6.

FIGS. 10 and 11 show schematically a portion of a building comprisingany sort of structure, two floors 111 and 112 of which are shown, saidstructure supporting a facade with a metal skeleton, one vertical column113 of which is represented schematically. A continuous wall 114 isattached to this skeleton, consisting specifically of double glazedwindows 115 and opaque insulating panels 116 disposed between thedifferent levels of windows and usually called back plates. Dependingupon need, similar insulating panels are disposed between the windows onthe same level. The facade is covered with a glass screen 117 formingthe exterior dressing of the facade and also extending in front of bothwindows 115 and opaque panels 116. This screen is composed of fixedpanels 118 and movable panels 119, each of which comprises an exteriorplate 120 made of tinted and/or reflecting glass and a metal frame 121disposed on the back of this plate. Frames 121 of the panels areattached to columns 113 so that a ventilation space 122 subsists betweenthe glass plates 120 and the wall 114. Thus, the glass screen 117ensures a certain thermal regulation effect for wall 114, by on the onehand protecting it from sunlight and, in space 122 where the air isgenerally hotter than outside, permitting convection circulation of airentering this space as indicated by arrow A, next to a lower edge 123 ofthe screen, and leaving at the next upper edge of said screen. When thisheated air passes in front of a window 115, as is the case in FIG. 10,it offers the advantage of heating the window in winter; but in thesummer, there is the disadvantage of overheating the area of the windowwhere the non-working frame 124 and the opening frame 125 may be metaland thus good heat conductors. Furthermore, the current of hot air isparticularly disagreeable in the summer when one opens the window.

The bothersome effects mentioned above are in large part avoided thanksto movable panel 119 preferably attached on the front of each window115. Panel 119 is horizontally movable in a direction perpendicular tothe facade, while remaining parallel to itself, between a closedposition, shown in FIG. 10, and an open position, shown in FIG. 11. Thepanel frame is supported near its four angles by sliding arms 126attached to columns 113 and controlled by user 127 by means of a controlbutton 128. In addition, a deflector is formed by a movable plate 130extending horizontally between the two lower sliding arms 126, slightlyabove the level of lower rim 131 of the movable panel, said plate beingconnected to the two arms so as to be displaceable with the panel. Itsconstruction will be described later in more detail.

When panel 119 is in its closed position as in FIG. 10, deflector 130 isat least partially retracted and allows air to pass between it andscreen 117, so that warm air can rise in front of window 115 as usual.Glass plate 120 of the movable panel is in the same plane as those ofadjacent fixed panels 118. The user 127 can activate button 128 to placemovable panel 119 in the open position of FIG. 11, for example if hewishes to open window 115 for air when it is hot. Deflector 130 thencovers the portion of space 122 situated below the window so that thecurrent of air rising in this space is deflected toward the outside. Atthe same time, outside air may be introduced behind panel 119 abovedeflector 130 and on the sides, to aerate the area of window 115 and/orrise in the upper portion of the ventilation space.

FIG. 12 shows more detail of the disposition and functioning of movabledeflector element 130. This element constitutes a sort of horizontaltablet and is formed by a sheet of steel bent into a "U" with a back rim132 and a forward rim 133 directed downward. Element 130 is locatedabove a fixed element 134 attached to the non-working frame 124 of thewindow and having an ascending rim 135 situated between the two rims 132and 133 of movable element 130. When panel 119 is in the closedposition, shown by solid lines, the exterior rim 133 of movable element130 is adjacent fixed element 134 and allows air to rise along arrow Cfrom space 122. When panel 119 is in the open position, shown by dottedlines, movable element 130 and fixed element 134 are joined at theirrespective rims 132 and 135 and thus form a continuous deflector whichdeflects the air rising along arrow B. A space in the form of slot 136between element 130 and glass plate 120 remains constant and in the openposition may allow outside air to enter.

FIGS. 13 through 15 show more detail of the construction of movablepanel 119 and of one of the sliding arms 126 supporting the lowerportion of the panel and movable deflector element 130. Panel frame 121is made in a similar manner to frame 11 and 71 of the precedingexamples, with a pair of light metal vertical profiled elements 137,connected by two horizontal stainless steel rods 138. The rods aredisposed at the level of the window frame so they do not interfere withthe view. The extremities of profiled elements 137 are laterallyattached to arms 126. In certain cases, a supplementary guide arm (notshown) may be provided halfway across the span of the window andattached to rod 138.

Each arm 126 consists of a light metal profiled element engaging tworotating pulleys 140 held by a support 141 attached to column 113. Onthis profiled element there is affixed a horizontal rack 142 on whichportion 143 is engaged, supported by a rotating shaft 144 held by column113 by means of bearings 145. Shaft 144 extends as far as the area ofthe top of panel 119 to drive the two arms 126 of this panel extremityin synchronization. A mechanical connection (not shown) may even beprovided between arms 126 of the two panel extremities. Rotation ofshaft 144 may be manually controlled. In the present case, it iseffected by means of an electric motor 146 controlled from a distancewith button 128 (FIG. 11). The movable element of deflector 130 isattached directly to a horizontal flange 147 of the profiled elementforming arm 126.

In a facade of this type, if glass screen 117 comprises a plurality ofhorizontally movable panels 119 remaining parallel to themselves andcontrolled in synchronization, specifically in different groups ofpanels, an interesting visual animation effect on the facade may beattained. For example, coordinated movement of panel groups may becontrolled with a computer, in combination with the control of air ventsor other means acting to ventilate space 122 situated behind screen 117,or not. Note that other similar effects relating to ventilation orfacade animation may be obtained by means of movable panels movingaround a horizontal axis. With frame 121 described above, attaching thepanel to a horizontal axis supported by a column 133 presents nodifficulty.

FIGS. 16 through 18 concern a panel 149 for facing a facade, comprisinga rectangular exterior plate 150 and a metal frame 151 which comprisesfour angled pieces 152 connected in twos by traction elements, that istwo horizontal rods 153 and two vertical rods 154 made of steel,preferably stainless steel. Rods 153 and 154 are similar to those of thepreceding examples, with threaded extremities for holding screws 155. Incertain applications they may be provided with a protective ordecorative cover 156, perhaps made of synthetic material. Each angledpiece 152 comprises a flat back 158 in abutment with the back of plate150, a horizontal flange 159 and a horizontal flange 160 forming rimswhich cover the corresponding edges of the angle of plate 150, and rimswith angle plates 161 and 162 disposed in front of flanges 159 and 160and hooking onto the exterior surface 163 of plate 150. Preferably, anelastomeric sheet 164 is interposed between plate 150 and thecorresponding surfaces of angled piece 152. In the back, back 158 of theangled piece has a vertical rib with a flat core 165 and a tubularportion 166. Core 165 is traversed by horizontal rod 153, whose screw155 abuts the core, while tubular portion 166 receives vertical rod 154and also serves as a contact for its screw. With such an arrangement,the horizontal and vertical edges of plate 150 may be entirelyunattached to any structural elements, outside of the angled pieces ofthe panel. They may be located very close to the free edges of theadjacent panels, forming a facade facing which appears to be continuous.Furthermore, it is easy to block the small space between two panels bymeans of a prefabricated compressible connection. Another advantage offrame 151 is that it is no longer necessary to bevel the edges of plates150 because the frame is visible on the exterior only at rims 161, 162in the angles of the panel. If necessary, oblique rims may be providedand the plate edges bevelled only in the area of the angles.

Exterior plate 150 may be of any type whatever provided it is rigid. Inthis example it is a double glazed insulating one such as those used forwindows, consisting of two plates of glass 167 and 168 spaced apart fromeach other and connected on their periphery by a connection 169 ofsynthetic material. This type of plate may also be used with frame 11,71, 121 described above.

FIG. 19 shows an advantageous way to affix panel 149 to verticalprofiled elements 170 of a facade structure by means of supports 172engaging vertical rods 154. Each support 172 is a profiled element oflight metal or steel, having a tubular portion 173 engaging rod 154 anda flange 174, flat or profiled, attached to column 170 by means of bolts175. Four supports 172 are sufficient to rigidly affix panel 149 to thestructure, its weight being supported by contact with two upper angledpieces on upper supports 172. The panel may also be pivotably mountedaround one of the vertical rods 154, thus forming a hinged axis, ifsuitable supports are provided for the other panel extremity. Many othertypes of attachment for such a panel are possible, especially by meansof protruding elements on the back of each angled piece 152.

FIGS. 20 and 21 show different variations of panels similar to panel149, but whose frames have differently designed traction elements. Inthe case of FIG. 20, plate 150 is supported by four angled pieces 172which are pulled toward each other by means of one or more steel cables173 passing over rounded projections 174 on the back of each angledpiece. In this way the metal frame is nearly invisible along the edgesof plate 150. The panel attachment means may be provided on projections174 or next to them.

In the example of FIG. 21, four angled pieces 176, each provided with anattachment means 177 for attaching the panel to the facade structure areclamped onto plate 150 only by means of two diagonal steel rods 178.This solution is especially useful in a panel with an opaque facing.

Many other embodiments and ways of attaching prefabricated panelsaccording to the present invention are possible as a function of theirspecific application. One important advantage of a facade constructed inthis way is that the panels forming the exterior facade surface are notseparated by any construction element which is conspicuous or evenvisible from the outside. Actually, these panels are separated only byhollow joints 4, 5, 65, 66, that is, the empty spaces which are narrowenough to be poorly lit from the outside and thus to appear as thin darkareas with an invisible base. The oblique rims of the metal frames maybe colored to match the plates they support or hidden by profiledelements made of synthetic material which may be darkly colored, forexample, so that from the outside of the facade virtually only theexterior plates and the dark lines formed by the hollow joints are seen.In addition to the esthetic effect, a facade covered with such panels isalso advantageous from the point of view of maintenance and weatherresistance, as the the structure is completely covered by the exteriorpanel plates. Moreover, these plates form a semi-continuous skin whichallows facade ventilation behind the skin.

We claim:
 1. Facing or window panel designed to form a prefabricatedelement of the exterior facade surface of a building and comprising atleast one rectangular exterior plate (10, 70, 100), especially made ofglass, stone, fibro-cement, synthetic material or the like, and a metalframe (11, 71, 121, 151) supporting the said exterior plate and providedwith means to attach it to a facade structure or to a window, said framecomprising at least one pair of support elements having metal rimshooked onto at least two opposing edges of the exterior plate to holdsaid exterior plate, and traction elements extending between the twosupport elements of each pair behind said exterior plate and connectingsaid two support elements so as to pull them forward each other and gripthe exterior plate between said rims said traction elements beingcapable of varying the spacing between the two support elements of eachpair, and at least one of the remaining edges is substantially free ofany visible exterior support.
 2. Panel according to claim 1,characterized in that each of the traction elements comprises a steelrod (13, 76, 138, 153, 154, 178).
 3. Panel according to claim 1,characterized in that the said rod has threaded extremities (27, 77)disposed through transverse holes in said support elements and providedwith clamping screws (28, 78, 155).
 4. Panel according to claim 1,characterized in that the said traction elements comprise at least onesteel cable (173).
 5. Panel according to claim 1, characterized in thatthe panel support elements comprise two metal profiled elements (12, 72,137) disposed along two first opposing edges of the exterior plate, andat least two traction elements (13, 76, 138) disposed in parallel to twoother edges of the exterior plate, these two other edges (14, 15) beingunattached to any frame element outside the area of the plate angles. 6.Panel according to claim 5, characterized in that each one of thesupport elements (12) comprises, at at least one extremity of the saidprofiled element, a transverse stop (30) abutting the edge (14) of theplate which is perpendicular to the said profiled element.
 7. Panelaccording to claim 1, characterized in that the panel support elementscomprise four angled pieces (152, 172, 176) connected in twos by thetraction elements (153, 154, 173, 178) and each having two of the saidedges (159, 160) perpendicular to each other for hooking onto an angleof the exterior plate (150), and in that the four edges of the saidplate are unattached to any frame element between the angled pieces. 8.Panel according to claim 1, characterized in that the said exteriorplate (150) is a double glazed insulating plate.
 9. Panel according toclaim 1, characterized in that the said exterior plate (100) is made ofplate glass.
 10. Panel according to claim 1, characterized in that oneof the elements (72) of the said pair of support elements is providedwith hinges (85) disposed to support the panel (62) and allow it topivot, the other element (73) of the pair being provided with lockingmeans (88) to selectively block the panel from pivoting.
 11. Buildingfacade comprising a facade structure and an exterior facing consistingof at least one rectangular exterior plate (10, 70, 100), especiallymade of glass, stone, fibro-cement, synthetic material or the like, anda metal frame (11, 71, 121, 151) supporting said exterior plate andprovided with means to attach it to a facade structure said framecomprising at least one pair of support elements having metal rimshooked onto at least two opposing edges of the exterior plate to holdsaid exterior plate, and traction elements extending between the twosupport elements of each pair behind said exterior plate and connectingsaid two support elements so as to pull them toward each other and gripthe exterior plate between said rims said fraction elements beingcapable of varying the spacing between the two support elements of eachpair, and at least one of the remaining edges is substantially free ofany visible exterior support.
 12. Facade according to claim 11,characterized in that the said support elements (12, 72, 73, 137, 152)of the metal frame of a panel are hooked by their edges to at least twovertical opposing edges of the exterior plate (10, 70, 100, 120, 150) ofthe panel and are connected by horizontally disposed traction elements(13, 76, 138, 153), the horizontal edges of said plate being unattachedto any frame element outside of the area of the plate corners. 13.Facade according to claim 12, characterized in that the said means forpanel attachment comprises supports (33) attached to said structure andequipped with upwardly facing hooks (34) in which the traction elements(13) of the panel engage.
 14. Facade according to claim 12,characterized in that the said structure comprises a wall having atleast one window (63, 115), in that the said exterior facing is composedof panels (61, 62, 118, 119) of plates of glass, and in that theseplates form a vertical screen (117) extending in front of the said walland the window, at a distance from them, so as to form a ventilationspace (122) between them and the screen.
 15. Facade according to claim14, characterized in that the said window (63) comprises a non-workingframe and an opening frame on a vertical axis, and in that one (62) ofthe exterior facing panels, situated in front of the window, issupported by the opening frame (82) of the window so as to be able topivot with it toward the inside of the building.
 16. Facade according toclaim 15, characterized in that one of the said support elements (72) ofthe frame of said panel (62) is provided with hinges (85) with verticalaxes, in that the means for attaching panel (62) comprise metal clamps(86) supporting said hinges and affixed to the opening frame (82) of thewindow, and in that, in the area of said hinges, the panel (62) extendsin front of the non-working frame (83) of the window so as to hide it.17. Facade according to claim 16, characterized in that the said metalclamps (86) are angled so as to form, between the window and the panel,a space (90) forming a housing for an awning (91).
 18. Facade accordingto claim 14, characterized in that one (119) of the exterior facingpanels, situated in front of the window (115) is movably attached tosaid structure in relation to the adjacent panels (118) situated aboveand below it, said panel (119) being movable between a first positionwhere its glass plate (120) is in the same vertical plane as those ofthe adjacent panels, and at least one second position where at least thelower edge (131) of said plate is distance from said vertical plane andleaves an air passageway between the ventilation space (122) and theoutside air, and in that said panel is connected to a control means(128, 142-146).
 19. Facade according to claim 18, characterized in thatsaid movable panel (119) is movable in the horizontal direction,perpendicular to the facade, while remaining parallel to itself. 20.Facade according to claim 18, characterized in that the said movablepanel (119) is connected to a movable element (130) of a deflectordisposed along one lower edge of the window, and in that, when themovable panel is in said second position, the deflector extends abovethe ventilation space (122) so as to deflect a current of air rising insaid interval outside.